^ THE RELATIVE STRENGTH OF 



;..k tlu- fact that the average age at starting the occupation of 

 innkeeper i- tar higher than that of entering the church, because 

 ultimately to keep an inn is the ambition of men, who begin life in 

 a variety of other callings. As a last illustration we may take the 

 problem of the effect of the drinking of the father on the health and 

 ability of the offspring. We might find that the father who drinks 

 had abler and physically better developed sons than the non-drinker. 

 Yet on closer investigation it might appear (i) that on the av 

 the drinker was the abler workman, and thus the apparently gr 

 ability of the offspring was really an hereditary matter, (ii) that the 

 abler workman got higher wages, and thus, notwithstanding the 

 drink, the food at home, especially perhaps in the earlier days of the 

 family life, had been ampler and of better quality. There is hardly 

 a single problem of parental occupation and habit, of home environ- 

 ment and school influence which is not of the greatest complexity, and 

 full of pitfalls for even the most cautious statistician. And if this be 

 true, what must be said for the philanthropist and social reformer who 

 without hesitation preach that social salvation lies in this or that line 

 of conduct? What must be our judgment of the "practical man" 

 and the statesman who legislate in the direction indicated by the 

 falling scale of popular opinion, without any real examination of the 

 intense complexity, the subtle biological effects of even slight changes 

 in the factors on which our national weal depends? 



A factory act may be carried owing to a wave of popular emotion, 

 which paints the horrors of child-labour in the mills. Twenty years 

 afterwards it may become apparent that children were taken care of 

 because their labour was of value, but that their value depending on 

 their labour, they are, since the act, an unmarketable commodity and 

 have ceased to be born on this very account 1 . 



What guide can we take to indicate the path of true social reform 

 through such a tangle of cause and effect as we find involving the 

 relative influence of nature and nurture on human life? It is not 

 enough to show that results are associated with this or that factor; 

 we have a vast complex of associated factors, and out of this complex 

 we have in some way to pick out the more important and in a certain 

 sense the fundamental factors. The only effective method by which 

 it seems possible at present to approach such a problem is that of 



1 For a fuller discussion of this point see Pearson : The Problem of Practical 

 Eugenics. Galton Laboratory Lecture Series V ; and Elderton : The English Birthrate, 

 Part I, North of the Humber, Galton Laboratory Memoirs. Nos. XIX and XX. 



